Phase contrast CMR in the descending aorta as a supportive reference for severe aortic regurgitation

Accurate grading of aortic regurgitation (AR) severity is crucial for treatment decisions. This study aimed to determine whether phase contrast cardiac magnetic resonance (PC-CMR) in the descending aorta can be used as a supporting reference for grading of the AR severity in patients with chronic AR. PC-CMR was performed both in the ascending and descending aorta of 191 AR-patients. Regurgitation thresholds in the descending aorta for hemodynamically significant AR [regurgitation volume (RVol)_DA and fraction (RF)_DA] were determined in 41 well-controlled patients and then validated in a cohort surveyed for AR in our clinic. Myerson's outcome-based thresholds (RVol > 42 mL, RF > 33%) served as reference. For comparison, holodiastolic flow reversal (HFR) was determined. Regurgitation measurements in the descending and ascending aorta were strongly correlated (RVol: R ≥ 0.92; RF: R ≥ 0.85; p < 0.001). Diagnostic performance of RVol_DA>17 mL and RF_DA>23% was high (sensitivity: 92%, 83%; specificity: 95%, 93%) and more patients with significant AR were identified using these PC-MRI based thresholds [RVol_DA>17mL (13%) and RF_DA>23% (15%)] than with HFR alone. PC-CMR in the descending aorta has the potential to reliably grade AR severity in patients with chronic AR and thereby may serve as a supportive reference in the decision-making regarding optimal timing of intervention.